RNA-based studies of Duchenne Muscular Dystrophy: post-transcriptional control and role of non coding RNAs in normal and dystrophic muscle development

Among primary myopathies, the Duchenne muscular dystrophy (DMD) is certainly the most relevant because of diffusion and severity. The defect resides in mutations in the X-linked dystrophin gene: in the absence of such protein the muscles gradually begin to deteriorate. Since this disease is caused by mutations on a single gene (monogenic disorder), it was considered from the very beginning for a gene therapy approach. Several years ago we have pioneered a strategy, different from gene replacement, consisting in the modification of the dystrophin mRNA: by acting on a cellular procedure called RNA splicing and preventing the inclusion of specific mutant exons in the mature mRNA (exon skipping) it is possible to restore the production of a shorter but functional dystrophin protein. More recently, we have extended the analysis to those proteins that control the dystrophin mRNA splicing. In one case of study we found that the lack of a specific protein (Celf2a) induces natural skipping of exon 45, a mechanisms that allows the recovery of dystrophin synthesis in a DMD subject with exon 44 deletion. One goal of this project is to design and set up genetic and/or pharmacological treatments to regulate theCelf2a activity and to test them for their capability to induce the skipping of exon 45. The finding of such possible inhibitors could open the way to the pharmacological treatment of those patients where skipping of exon 45 could be curative. In more general terms, this study also points to the relevance of studying the genomic milieu of different patients in order to facilitate the clinical development of personalized therapies. The second line of activity aims at discovering the role in DMD pathogenesis of novel classes of non-canonical RNAs, the long non-coding RNAs (lncRNAs) and the circular RNAs (circRNAs). These molecules have been recently discovered and found to play important roles in cell function; moreover, their deregulation has often been associated to different pathologies. This new and innovative field of research holds promise for a significant increase in our understanding of basic molecular processes controlling muscle function and should also constitute a vast and largely unexplored territory for the development of novel therapeutics and diagnostics.